For centuries, mankind has feared what lies beneath the waves of the seas, oceans and inland bodies of water.

Fishermen, pirates and naval fleets have all documented sightings of weird and wonderful sea-dwelling creatures, stirring the imagination and creating great tales from aboard sailing vessels.

Which are myths and which are facts? You decide...

Bobbit Worm - This long, predatory worm lives at the bottom of the sea with its slender body buried deep into the sand or gravel. It has 5 antennae that can detect close prey as well as huge claw like teeth that clasp shut on their prey so hard that they have been known to cut fish in half! They are also known to inject a toxin to stun and disable their prey, making them easier to digest.

Fiji Mermaid - First seen in Japan in the early 1820s, but caught somewhere off the Fiji islands, this strange creature was a hybrid of both mammal and fish. From its head to breast it is likened to a small monkey complete with incisor teeth and hair, and the rest of the body is that of a long fish, hence the mermaid connotation. Often seen in 'freak shows' in America in the 1800s.

Megalodon - The largest of all sharks ... ever! Recorded sizes reaching up to 18 metres but possibly grows larger. These are known to prey on other sharks, killer whales, seals, giant turtles and even whales.

Kraken - This huge animal is best described as a giant squid and reaches lengths of up to 50 feet! First recorded in the 13th century by Icelandic fishermen, the Kraken has been reported to attack and break ships into pieces to prey on the men aboard.

Leviathan - The original 'Sea Serpent' originating from the Middle East. Often described as a dragon-like creature with horns and a snakes body. This ancient creature is said to guard the gates to Hell.

Loch Ness Monster - 'Nessie' is said to inhabit Loch Ness in the Scottish Highlands. First spotted by an Irish monk as far back as the 6th Century, Nessie is described to look like a 'water dragon' and witnesses say that a long neck and head protrude from the water.

Poseidon - Second son to Cronus and Rhea and one of twelve Greek gods, ruler of the waves and protector of seafarers. It is said that the earth was split into three with Zeus receiving the sky, Hades the underworld and Poseidon the sea. Poseidon also had a son, Triton.

Narwhal - This medium-sized whale is found around Greenland, Canada and Russia. The males have a very long 'unicorn' like tusk that protrudes from an elongated canine tooth. Narwhals can reach around 18 feet in length and live up to 50 years old!

Sirens - Described sometimes as part woman and part bird, these creatures are reported to have beautiful singing voices that lure sailors towards the rocks where they dwell. Once shipwrecked, the sailors drown or are torn apart by these dangerous creatures.